In smart grid, the scale of pole devices that monitor the health of power lines is already large, and with the upgrade of the smart grid, the number of these resource-constrained devices is further increasing. These devices are easy targets to security attacks due to wireless access communication and due to weak passwords used to access and read telemetric data by the pole maintenance personnel.
In this paper, we present a scalable and automated password-changing protocol framework for unique authentication of human personnel (driver) with large scale of pole devices, and for secure collection of telemetric data from the pole devices. Our protocol framework employs physical per-driver, per-pole-device information as well as fractal functions to generate new unique passwords and secrete keys for different drivers over a large scale of pole devices and over long periods of time. Our experiments confirm that the password-changing protocol authenticates and transmits pole device data securely and in real-time under varying maintenance scenarios.